Pulse synchronizing circuits



Dec. 15, 1953 w, BAKER L 2,662,982

I PULSE SYNCHRONIZING CIRCUITS Filed Feb 19. 1951 s Sheets's-Sheet 1 pair/41a D V/C g [fl/9y arc/4mm! 2 Output flaw/v5 ,3 anal/m9)? i l I I 0 l l I L)? I v l I I l l I v I H I v 1 a '4 l r J v Inventor 6 7 MATTHEW WILLIAM BAKER a F /G. 2. DEREK ANTHONY umsnwooo RUSH Dec. 15, 1953 M. w. BAKER ETAL PULSE SYNCHRONIZING CIRCUITS 5 Sheets-Sheet 2 Filed Feb. 19, 1951 MON.

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R u Wv U W m T n m M m NOW QQQ wsw D 19 M. w. BAKER EI'AL 2,662,932

PULSE SYNCHRONIZING CIRCUITS Filed Feb. 19, 1951 3 Sheets-Sheet 3 2 w q I a l 8 o I "a l m m |0-/\/\Ar I 1% I Q a I I m Q m B 8 I l m m I Q .3 I I I0--/V\/\ I I I v I F) I b I s l I I a I a L I I) Q wk Inventor MATTHEW WILLIAM BAKER 8 DEREK ANTHONY UNDERWOOI? RUSH Patented bee. 1 5,

ru sr: s nc aceaesz V is HRONIZING CUITS I a w Matthew William Baker, Blaekheath, London,-

and Derek Antho'ny Underwood Rush, Ealing; London, England; assignors to The Sperry:

GyroscopevCompany Limited, Brentford; ;Eng-

land,a Britishcompany Application February 19, 1951, emi

- 14 Claims.

invention relates-to apparatus for producing accurately timed high-power'electrical pulses;

e. 'g., for; energising a magnetron/and p'articuratron. The delays so introduced are liable to remain substantially constant for a series ofconsecutive pulses, but "to change slowly, so as to havediiferentvalues for series of such pulses at difierent p I The object of the present invention is to providevmeans whereby the slowlychanging systematic' delays'of the amplifier or relay device used in such apparatus are automatically compensated for, thus reducing the error in the timing of the output pulses to negligible proportions.

The invention consists in apparatus for producing a series of recurrent high-power electrical pulses in a predetermined time relationship with recurrent'low power primary signals of the kind i'n which a relay device, such as a spark or gas discharge tube, is'employed for providing high-power pulses in response to triggering pulses wherein; in order to compensate for variable systematic delays in the operation of the relay device, the primary signals are applied to a controllable delaying device arranged to derive the triggering pulses from the primary signals after a time delay that may be varied'by means of a control quantity; wherein means are providedfor producingreference signals delayed with'respect to the primary signals by a fixed accurately-de-- termined interval wherein the reference signalsand monitoring signals derived from the highpower pulses areto gether passed to a timing comparator which derives from "theman error signal indicativeof the time interv'albetween the reference signals and the -monitoring signals; and wherein the controllable delayingdevice is actuated in accordance with said error signal to bring the high-power pulses substantially into syn'chronis'm with the reference signals.

The invention will now be described with ref erence to a particular embodiment in which highpower pulses for"*energlsing a magnetron are provided by 'a;-thy'ratron relay device receiving controlling impulses from oscillator unit. V

- in the accompanyingidrawings Fig. 1 is a block schematic diagram showing the embodiment of the invention described. I 3

Fig. 2 shows diagrammatically some of the wave forms that occur in the apparatus described.

. Figs. 3 and 4 are simplified circuit diagrams of portions of the apparatus. Referring to Figs. 1 and 2 a .c'rystal'controlled oscillator unit I provides two" output signals namely, an advanced or primary signal A, which is eventually used to provide triggering pulses C for a thyratronl, and a. timing orreferenc'e signal B which defines the instants of time at which the high-power output pulses'providedby thyratron 4 are required. The total time. in-

terval, herein referred to as To, between the pri-; mary signal A and the reference signal B must.

be accurately "constant. -Means* for producing two accurately spaced outputsfrom a-crystalcontrolled oscillator are 'Well known and such" means form no part of the present invention;

' The primary signal-A passed through a controllable delaying device 2 whichderives from it triggering pulses 0 each delayed behind the cor-,

responding primary signal A'by a time interval T1. The'delaying-device 'Zis such that this delay time T1 is controllable in dependence on a control voltage applied'to it. The triggering pulses C are appliedto the control grid of the thyratron, which provides the high-power out.- put pulses after a further time delay, referred to hereinafter as'Tz, whichirepresentsth'e slowly changing systematic delay for which compensation is required. Monitoring pulsesD are derived as a fraction of the .thyratron output pulses, and these 'are passed to 'the timing comparator. 40 :3, which also receives atiming or reference sig nalB from the crystal-controlled oscillatorls The timing comparator 3 develops'an error signal proportional to the time diiference between the monitoring pulsesD and the reference signa1 B. This error-signal is applied as the con-'- trol voltage to'vary the'timev delay Tfi introduced by the controllable delaying ":device 2, by which 1 the triggering pulses C'are'delayed behind the primary signal A. The device is so arranged that 5 IT1 is either increasedor decreased under the continued application of the control voltage until T1+Tz becomes substantially equal to To, in e; until the thyratronoutput pulses become sub synchronised withthe reference I sigstantially "nal Br UNIT El) a I crystal-controlled" The circuit of a preferred form of the controllable delaying device 2 is shown in Fig. 3. The primary signal A which consists of a train of positive pulses from the oscillator l, and which may, for example, have a repetition frequency of 3,000 pulses per second is applied to terminal 200 and is inverted wan amplifier which is of conventional design. The resulting negative pulses A are applied over capacitor 203 to the grid of valve 205. The two valves 2% and (which may be the two portions of a double-triode valve) are connected as a sg called cathodecoupled flip-flop circuit withyalve 2E5. norma l conducting. Such a circuitlhas one stable and one unstable condition of operation. It is nor mally in the stable condition but the arrival of the negative pulse A causes it change to the unstable condition in which it remains "fora period of time determined by the characteristics of the valves and the values of the associated components and also by the potential of terminal 202;" The error signal produced by the timing comparator 3 is applied to this tenninal and thus controls the length ofv time the circuit remains in the unstable condition. The action of the circuit on receipt of .a ne ative pulse A is as follows: I

The negative pulse A. applied to the grid 01? valve 205 causes it to cease to conduct and thus produces positive pulse E at its anode and a negative pulse E at itscathode. Positive pulse is potentials applied to their grids over resistors H2 and 220 respectively. The negative pulse G has no efiect on the state of the two valves, but when the positive pulse I-I arrives, valve 2 l3 commences to conduct. The resulting pulse of current through the primary winding of transformer 2 I! induces a large voltage inthe secondary winding which is applied through capacitor 218 to the grid of valve 2l6 in such a sense as to make it positive with respect to the cathode. Thus valve 2I6 is caused to 'conduct and maintains the current flowing through the primary winding of transiorrner 211. The positive voltage on the grid of valve. 215. is high enough to cause grid applied to the grid .of valve 209 over capacitor 208. 7

Until the arrival of positive pulse valve 209 was prevented from conducting by the negative bias applied to its grid over resistor 222 an also by the positive voltage on cathode produced by the current flowing through yalye 205. The combined efiect of the positive pulse E applied to its grid and the ne ative pulse E! pplie t ts cathode cause valve 2-09 .to oondu t- Cu ren through valve 2.09. then makes the cathode of oth valves become positive a ai A ter a p riod of time determined by the che acteri iiosoi the vales, the yalues of capa itor .9.8 a d e: sisters 20.6 and 2 .1 and, the positive potentia o terminal 12M. the potenti l oifie en e i: won t grid and cathode ,oi valve 305 w ll. ea a a e at which the valve will a ain spi e t co duct. A ne ative pulse. will hen a pe r at h anode is fed oy r capacit 208 o th rid of al-ge 2.09. T e com ined st e t o t is nosetiye puls t e in reasin osit ve pote t al 9.11

the cathode and the negative bias applied over resistor 222 will cause the valve toceaseto con; duct. Thus the circuit restored to the state it was in before the arrival of A.

When valve 203 commences to conduct, its anode potential drops, and when it ceases to con: duct, the anode potential rises. Thus, a negative square wave F is effectively produced at the anode of valve 2,05. This s uare wave is d fferen ia e by t e resistance-capacity combinati n :2 nd 2 l2, and the resulting positive and negative pulses G and H are appl ed to the rid of valve M3, he n ative pu se G ooourse ubs antia the sa e time as the tri er pulse .9... .while. the osithe pu e H ccurs at an interval after this d termined by th voltage on term-ina1v 2.02, It is hi yariable interva is sed to vary he ime i. V

Yol es 213 and H5 w ich pain may be. two o ions o a nob of the same t pe as 1 re semen-tea ter o as mally non-conductmg uitare per.- a result of the negative current to flow so that capacitor 2I8 charges through the grid-cathode path of the valve and also through the higher impedance parallel path through resistor" 220'and the negative bias supply. Thus the grid of valve 2 I6 becomes less positive, and eventually becomes sufficiently negative with s e t t t c meos is au t e v v to ce to conduct. The resulting decay of current through the primary winding offtr'ansformer 2l'1 induces a voltage in the secondary winding in such sense that the ungrounded end of th'e'winding becomes negative. This negative potentialis added to the voltage across the capacitor 218, due to the h r aw-umele erein nd app i d to he gr d of t e alve i 'd' v i still more negative, thus accelerating thedecay of current through th valve. A diode valve 21'9 is connected between this grid and a'point that is at a moderately'largje negative potential .with'r'ef i nc to s oun s prevent th r of lve 6 reach n an exc ssive nega ve o ential, since the diode will conductv as soon as itsanode becomes positive'witlrrespect to its cathode. Thus, after the occurrence of thepositivepulse H, the potential of' terminal 22,! "rises sharply to a high positive value, followed by" a negative swing, both being of quasi-sinusoidal io'rrn. Tor minal 2'2l"isc flied? m 31 of e entional cathode iollo' er 223 the output of which rovi es" the firing pulse ,0 for the'thyratron (Fig, 1). It canbe seen that this firin pl-lllse C occurs at a timeafter the occurrence oi'the pri: mary signal A 'whiclilis oontrolledby the potentialofterrnina1202,

A simplified ciifcuit of a preferred form of the timing bmparator 3 "is shown in Fig. a. The rei'ernce'jsignal 'B from the oscillator l, which is in the'forrn of a train of positive pulsesjis passed through a pulselengthenershown generally at 309 by niea'iisfof which'each'of th'e'pulses is lengthened to, say, 30".microseconds sothat it is of the form shownat B. The pulseelengthene ing circuit 30,; comprises two valves 3 l3 and 3E5 h h ma be the two porti ns'o a o bl triode valve) connected in a cathode coupled flip iiop circuit generally similar to the circuit o he wo lves 29? and 20. sh wn in F 3 his cuit one s a e n e u stable m di io o op ra ionis n a y n t e a le nditi n, t th a iva of t e s en em l B cau e it i han e to the s y eeoh t n w i h it rem ns fo a er od det ined y he haracteristics of the a ves an the v l s of the a ociated compon nts he. m tndd'f pe ati is asi lgws an a e 3 is oopdu iiea by 'resistor3l2, it isnegative with respect to the cathode, and the valve therefore does not conduct. When the positivepulse B is applied to this grid, over capacitor 3| I, valve 3l3 commencestoconduct. The potential of the anode therefore drops and a negative pulse is fed'to the grid of Valve 3E5 over capacitor 329. This negative pulse causes the valve to cease to conduct and thus reducesthe voltage drop across resistor 314. Valve 3l3 therefore continues to conduct, since its gridis onlyslightly negative with respect to its cathode. The potential of the grid of valve 3H5 commences to rise immediately after the termination of the negative pulse from the anode of valve 3I3, since the capacitor 329 charges through resistor 3l9. The component values are so chosen that at about the end of 30 micro-seconds the grid potential has risen to a value at which the valve 3l5 commences to conduct. The resulting current through resistor 3|4 causes the cathode potential of both valves to rise and cuts off valve 3l3. Thus the circuit is restored to its stable condition. When valve 3 I5 is cut off, the anode potential rises, and when it recommences to conduct, its'potential drops and thus a positive square wave of about 30 micro-seconds duration is effectively produced at the anode of valve 315. It is fed over capacitor 3!!! to the grid of valve 322.

The monitoring pulses D, which are derived from the thyratronoutput and which occur at the moment when the thyratron actually fires, are fed to terminal 300 and are lengthened into square waves D by the pulse-lengthening circuit 30I which is similar in action to the pulse-lengthening circuit 309 already described. The component values of this pulse-lengthening circuit are so chosen that a positive square wave D' of approximately 100 micro-seconds duration is produced by each monitoring pulse D.

The lengthened monitoring pulses D are applied over capacitor 302 to the grid of amplifying valve 305. This valve has its anode connected through the anode load resistor 306 to a point which is maintained at a potential of about volts negative with respect to ground by means of the potential divider comprising resistors 301 and 308 which are connected between the ground line and the 300-volt negative bias supply. The cathode of valve 305 is maintained by the potential divider 304, 33l (also connected between the ground line and the 300-volt negative bias supply) at a potential of approximately 290 volts negative with respect to ground, while the grid is held at 300 volts with respect to ground ,by resistor 303. Thus, the valve is normally nonconducting, but when the positive lengthened pulse D is applied to the grid, it conducts and an amplified and inverted version of this pulse D" is applied to the grid of valve 322.

Valve322is .normally noni-conducting, since thegrid is at the same potential as the anode of valve 305, namely about'20 volts negative with respect to ground. Under these conditions the cathode of valve 322isat ground potential, since no current flows through the cathode resistor 324. However, when the positive lengthened reference signal B is applied to the grid, the valve commences to conduct, and current through the valve produces a voltage drop across resistor 324, and thus charges capacitor 323. The valve continues to conduct and capacitor 323 continues to charge for the duration of pulse 3' or until of pulse D", which is in turn equivalent to the interval between the reference signal B and the monitoring pulse D.

-The voltage across capacitor 323 is smoothed 'by the combination of resistor 325 and capacitor 326 and is applied to terminal 202 in the controllabledelayingdevice (Fig. 3). v

In operation, when the apparatus is first switched on, the voltage applied to terminal 202 (Fig. 3) is zero, and consequently the length of square wave F is determined solely by the characteristics of the valves 205, 209 and the associated component values. Thus, positive pulse H occurs at the maximum possible time after the negative pulseG. The thyratron therefore fires some considerable time after the occurrence of the reference pulse B, i. e. T1+T2 To. As a result, monitoring pulse D will also occur some considerable time after the reference signal B and valve 322 (Fig. 4) will conduct for an appreciable portion of the lengthened pulse 3' before it is cut off by the arrival of the negative pulse D. Thus, capacitor 323 will be charged and a positive voltage applied te -terminal 202. This positive voltage will decrease thelength of square wave F and consequently cause pulses H and C to occur earlier. Thus, the thyratron also is caused to fire earlier, Eventually, a steady state 15 reached'inwhich the thyratron fires practically at the instant at which the reference signal B occurs. In this'state square wave D and B commence practically simultaneously and valve 322 only conducts for a period long enough to compensate for'the leakage of the charge on capacitor 323 through resistor 324.

What is claimed is: 1. Apparatus for producing a series of recurrent high-power electrical pulses in a predeter- 'minedtime relationship with recurrent lowpower primarysignals, said apparatus comprismg a source-of recurrent low-power primary signals, a relay device for providing high-power pulses in response to triggering pulses, controllable delaying means for deriving said triggermg pulses from said primary signals after a time delay that may be varied by means of a control quantity, means for producing reference signals delayed with respect to said primary signals by a fixed accurately determined interval, a timing comparator for comparing said reference signals and said high-power pulses, said comparator generating an error signal indicative of the time interval between said reference signals and said high-power pulses and means for controlling said controllable delaying means in accordance with said error signal to bring said high-power pulses'substantially in synchronism with said reference signals thereby to' compensate for variablesystematic delays.

2, Apparatus as claimed in claim 1 in which the error signal'is directly applied as a control quantity to said controllable delaying means to vary the delay introduced thereby.

3. Apparatus as claimed in claim 1 in which the primary signals and the reference signals are produced in the form of trains of electrical pulses.

4. Apparatus as claimed in claim 3 in which said trains of said electrical pulses are derived from the output, or a crystalcontmlled oscillator;

5. App a s; for p oducin a e ri r urr: rent high-power electrical pulses in: a predetermined time relationship with recurrent low-powerprimary signals, said apparatus comprising; a source of recurrent low-power primary signals,- a. relay device for providing high-power pulses; in response to triggering pulses, controllable dc.- laying means for deriving said, triggering pulses from said primarysignals :after; a time delay that may be varied by me n of a control quantity, said controllable delaying means. comprising electronic apparatus having one stable-and; one unstable condition,.of operation' and which is normally in the stable conditionbut is changed; to the unstable condition by eachof: the; pulses constituting the primary-' signal, said electronic apparatus remaining in the,,unstable condition. for a period of time. determinedrbyi-said control. quantity, after whichyperiod. it reverts';to the stable condition, meansxfor; producing reference signals delayed with respectito said primary sigi-- nals by a fixed accuratelydeterminedinterval, a

timing comparator for comparingsaid reference;

triggering pulses are derived from electrical pulses produced by the change in sai-deleotronic; appa-.

ratus from the unstable, to. the stable condition thereof.

'7. Apparatus. as claimedin claim 6. iii-which, the electrical pulses areproduced by a dififeren tiating device.

8. Apparatus as claimed in claim 7 in which he. tri ering. puls s are. prod c.ed.- bywa. blockin oscillator;devic.e. vv V 9. Apparatus. for}, producingya serieslof recur" rent. high-power electrical --pulses in: a predetermined time. relationship with recurrent.low,-pow,-

er primary signals, .saidiapparatus comprising source of recurrent; low-power primarysignals a relay i device. .for: providing high-power pulses in response. to tri gering pulses, contr ll ble w laying means for deriving said triggering pulses. from sai p imary-si nals after a time. delaythat. may. be. varied.,-by ,means of acontrolouantity... means. for producing reference, signals. delayed with respectto saidprimary signals by-a fixed:

accurately determined-interval, .a timingwcom parator for comparing. said reference, signals. and said. high-power pulses, said comparator comprising electronic gating. valve means said.- gate ing means being. normally nonrconducting and means for causing. said gating 'means to conduct; under the control .oi'said reference-signal. pulses and for causing, said gating meansto cease to. conduct under the --contr.ol of. said;.-hig h-.p ower.

pulses. wherebyflan error signal. is. developed in dependence, on. the, length of time forwhich said gating. means con ducts,- and means. for control-..

lingesaid :oontrollable delaying means; inaccord-.

12. Apparatus for producing a. series of recur-v rent high-power electrical pulses in a predetermined time relationship with. recurrent lowpower primary signals,.said apparatus comprising a source of recurrent low-power primary s ignalsh a relay device for providing high-power pulses in response to-triggeringpulses, controllable delaying means, for deriving said. triggering pulses. from said primary signals after a time delaythat may be varied by means of a control quantity, means for producing reference signals.

delayed with respect to said primary signals by a fixed accurately determined interval, a timing comparator foricomparing said reference signals and. said high-power pulses, said comparator comprising electronic gating valve means, said gating means being normally on-conducting, and means, for. causing. said gating means to conduct. under the control of said reference signal pulses and for causing saidgating means to cease dependence on the length of time for'which said gating means; conducts, said means for actuating said gating means including a pulselengthening circuit for lengthening each of the reference signal pulses before said pulses are applied to the gating valve, and-means for controlling said controlla-ble delaying means in accordance with said errorsignal to bring said high-power pulses substantially in synchronisrn with said referencesignals thereby to compensate for variable system'- atic' delays;

13. Apparatus as claimed in'claim 12 wherein said gating means further includes a second pulse lengthening circuit for lengthening each of said high-power pulses'before said pulses. are applied to the gating valve.

14. Apparatus asclaimed inclaim 13 in which the respective pulse. lengthening circuits oomprise an electronic apparatus' having onestable and one unstable condition of operation, said electronic apparatus beingnormally in the stable condition and being changed to the unstable con dition by the respective pulses, remaining thereat fora predetermined period of time and thereafter reverting to the-stable. condition MATTHEW." WILLIAM BAKER. DEREK ANTHONY UNDERVVOOD RUSH.

References Cited in the file oi this. patent FOREIGN 1 PATENTS Number 

